HVAC

1. Facilities Management and Design
Chapter 7
HVAC Systems

2. Thermal Comfort
 Balancing heat produced by one’s body with
surrounding environment.
 Body heat lost by convection, radiation, and
evaporation

3. Factors that influence comfort
 indoor temperature
 humidity
 air movement
 room surface temperatures
 overall air quality

4. Comfort zone
 Insert comfort zone chart

5. Heat sources
 Electricity– Used in all electric heaters. Requires no
flue. Usually most expensive.
 Natural gas – Clean burning. Flue required. Very
efficient. Delivered via underground pipe
 Liquefied petroleum – relatively clean burning. Requires
on-site storage tank. Delivered via truck.
 Fuel oil – tendency to create dirt/smoke. Requires on-
site storage tank. Delivered via truck. Various grades
available.
 Steam – more common in urban areas where available
from local utility or in large complexes with central
steam plant. Supply and return lines required.

6. Heating equipment
 Furnaces and Boilers
 Combustion efficiency
Furnace
Heat
Exchanger
Flue

7. Cooling Systems
 Boyles Ideal Gas Law
– Pressure
– Temperature
– Volume
 Certain gases react more
actively
– Refrigerants
– CFC’s
– HCFC’s

8. The Refrigeration Cycle
Compressor
Condenser Coil
Expansion Valve/ Metering Device
Evaporator Coil

9. Cooling system operating and
maintenance concerns
 Types of compressors
– Reciprocating
– Centrifugal
– Rotary
 Energy efficiency ratio (EER)
 Integrated part load values (IPLV)
 Environmental Protection Agency
– supervises aspects of refrigeration equipment maintenance
– importance of eliminating or reducing refrigerant leaks

10. Cooling system operating and
maintenance concerns
 Types of compressors
– Reciprocating
– Centrifugal
– Rotary
 Energy efficiency ratio (EER)
 Integrated part load values (IPLV)
 Environmental Protection Agency
– supervises aspects of refrigeration equipment maintenance
– importance of eliminating or reducing refrigerant leaks

11. HVAC system types
 Centralized systems; quiet
– two-pipe
– three-pipe
– four-pipe
 Decentralized systems; not as quiet
– heating and cooling sources in guestroom itself or along
outside wall
 Hybrid systems
– characteristics of centralized and decentralized systems

12. System types and maintenance needs of
HVAC systems for other building areas
 Air handling units
– Isolation of zones (housekeeping, kitchen, maintenance…)
 Packaged air conditioning units
– usually mounted on roof
 Maintenance issues
– Filter replacement
– belt checking and replacement
– cleaning of fans and heat transfer surfaces

13. HVAC controls
 Today’s controls are often electronic
 Thermostat
– enthalpy or economizer control
– Older control sensors—mechanical sensing
 Digital control systems
– variable air volume (VAV) systems
– load sensing equipment
– EMS sensors

14. Cooling towers
 Startup and shutdown concerns
 Inspection and lubrication of pumps and fans
 Removal of dirt and other debris
 Treatments to reduce bacteria, scale, and
corrosion
 Inspection of metal surfaces